1. Import your sound file into Audacity. You can just drag and drop.
2. In the bottom left of the window you'll see a small tab that says 'Project Rate (Hz).' In the dropdown under that, change the number to 32000. This will lower the file size by decreasing the sample rate and therefore quality of the audio, however this difference in quality is typically very trivial, if even noticeable. Some sounds might suffer more than others though, and if your sound quality decreases too much, changing it back to 44100 isn't too big of a deal.
3. Press CTRL + A.
On the toolbar at the top of the window, go to Tracks > Resample. The number in the dropdown should be the same as the number you used in Step 2.
Press OK.
4. On the tool-bar at the top of the window, go to File > Export > Export Audio. Save your sound file as WAV (Microsoft) signed 16-bit PCM
5. A window titled 'Edit Metadata Tags' will probably pop up. Near the center of this window you should a tab that says 'Clear.' Click that a couple times.
Press OK.
Your sound file should now be exported to the correct format, with a good balance between file size and sound quality.